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Subject[PATCH] ppp: fix out-of-bounds access in bpf_prog_create()
Date
From: Eric Biggers <ebiggers@google.com>

sock_fprog_kern::len is in units of struct sock_filter, not bytes.

Fixes: 3e859adf3643 ("compat_ioctl: unify copy-in of ppp filters")
Reported-by: syzbot+eb853b51b10f1befa0b7@syzkaller.appspotmail.com
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
drivers/net/ppp/ppp_generic.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 0cb1c2d0a8bc..3bf8a8b42983 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -564,8 +564,9 @@ static struct bpf_prog *get_filter(struct sock_fprog *uprog)
return NULL;

/* uprog->len is unsigned short, so no overflow here */
- fprog.len = uprog->len * sizeof(struct sock_filter);
- fprog.filter = memdup_user(uprog->filter, fprog.len);
+ fprog.len = uprog->len;
+ fprog.filter = memdup_user(uprog->filter,
+ uprog->len * sizeof(struct sock_filter));
if (IS_ERR(fprog.filter))
return ERR_CAST(fprog.filter);

--
2.24.0
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